In the purification of proteins, for example of interferons, by affinity chromatography there are already used adsorbents which consist of a carrier matrix, for example agarose, cross-linked dextrans or polyacrylamides, to which are directly covalently bonded as reactive groups colouring substances, especially triazine colouring substances such as the previously named (J. Chromatog. 165, 301 [1979]. Dean et al.), or antibodies which are specific for the proteins to be purified. Such adsorbents, which are suitable e.g. for the purification of interferon, are described, for example, in U.S. Pat. Nos. 4,172,071 (De Maeyer et al.), 4,278,661 (Knight, Jr.) and 4,289,689 (Friesen et al.), as well as in J. Biol. Chem. 256, 9750 [1981] (Staehelin et al.) and Scand. J. Immunol. 8, 429 [1978] (Berg et al.).